Vapor electric device and method of operation



Jan. 5, 1943.

N. r. GQRDON ETAL VAPOR ELECTRIC DEVICE AND METHOD OF OPERATION FiledMarch 28, 1941 Inventors: Newell TGor'don, Willis Rwhitneg,

Then" Attorney.

water-cool vapor though an emcient Pa tented Jan. 5,

FFICE varoa anaemic nsvrcs AND munch on Q OPERATION Newell '1'. Gordonnectady, N- Y.,

and Willis B. Whitney,'Scheassignors to-General Electric Company, acorporation of New York Application March 28, 1941, sem No. 385,642 1Claims. (cine-122) The present invention relates to vapor electricdevices, such as mercury lamps, and in particular to devices of thistype which are operated at relatively high vapor pressures. Ourinvention is applicable with especial benefit to high pressure vaporlamps which are provided with an envelope of substantially capillarydimensions in which under operating conditions there is a pressure of atleast several atmospheres. High pressure lamps are described in Bol,Elenbaas and Lemmens United States Patent No. 2,094,694, issued October5, 1937, and in Germer United States Patent No. 2,202,199, issued May28, 1940.

It is the object of improved apparatus and a method whereby vapordevices may be maintained at a desired operating temperature. In theoperation of vapor electric devices of high wattage consumption, it isnecessary to carry heat away more rapidly than the natural rate of heatdissipation. The progressive increase of vapor pressure otherwise wouldresult in correspondingly increasing the voltage necessary to operatethe lamp. Assuming the lamp to be operated from a supply circuit of highreactance, it eventuallywould be extinguished. In that event the devicewould not restart until it had cooled and the vapor pressure had fallenconsiderably lower than the pressure at which it ceased to operate. Thiswould result inunsatisfactory intermittent operation.

Another source of difilculty encountered in the operation of highpressure lamps is the devitrification of such parts of the vitreousenvelope as are in contact with the discharge, the devitriflcatlon beingespecially marked in the neighborhood of the electrodes. In the forms ofhigh pressure lamps shown in the above-mentioned 301 et al. patent inwhich the pressure of mercury vapor reaches many atmospheres duringnormal operation, the heat dissipation requirements are especiallyexacting.

High pressure lamps may be cooled by the circulation of water over theirsurfaces, such ar'- rangement being described in B01 and Lemmens UnitedStates Patent No. 2,094,695, patented October 5, 1937. Ordinarily, highpressure merour invention to provide an cross section on cury lampscons'ructed to operate with a, loading of more than 200 watts percentimeter of discharge columnhave been water-cooled. It is inconvenientand in electric devices. Water, al-

cooling medium, is subject to freezing. Also, water and other coolingfluids are subject to fouling, especially when recirculated in a closedsystem. Furthermore, liquid cooling some cases it is lnefllcient to.

,mally present during provided improved gas-cooling means,

is apt to be too energetic at the region where unvaporized material,such as mercury, is present. Ordinary air cooling, that is, cooling byair circulation, such as may be produced by a fan, is not suilicientlyeffective, particularly in lamps in which the discharge tubeis of smallbore as indicated in Fig. 1 and pressures of mercury vapor of at leastseveral atmospheres are noroperation. 2 of our invention, we haveconveniently using air as the cooling medium, by the use of which vaporelectric devices may be operated at high pressures with materiallyhigher wattage inputs than heretofore possible. Another advantageousresult of our invention is asreduction of devitriiication of theenvelope in which a high pressure discharge occurs and which is cooledin accordance with our, invention.

As will'be pointed out in greater particularity in the appended claims,the main novel feature of our invention comprises a method of andapparatus for applying to a vapor electric device high velocity jets ofcooling fluid, preferably air, the cooling jet having a dimension whichis materially smaller than the surface which is being cooled. Anotherfeature of our invention consists in applying such cooling jet or As aconsequence is apt to be most severe, that is, ordinarily adjacent theelectrodes. sists in applying the cent the surface to shown in theaccompanying drawing in which Fig. 1 shows a vapor lamp and jet coolingmeans in side elevation; Fig. mounted in a light projector; Fig. 3 is apartly sectionalized side view on an enlarged scale of a modification inwhich part of a tubular lamp is coated with a light-reflecting layer;Fig. 4 is a lines 4-4 of the modification of Fig. 3; and Figs. 5 and 6are perspective views of nozzles for furnishing cooling jets.

The lamp shown in Figs. 1, 2 and 3 comprises a tubular envelope{provided at opposite ends respectively with electrodes 3, 4 which mayconsist of tungsten. The of vitreous or fused quartz,

ing glass also may be used. ductors I, S are sealed into the envelope bya sealing glass as described in said 301 et al. Patent No. 2,094,694 andas well understood. These conducenvelope 2 ordinarily consists althoughheat-resistv jets to the envelope at a region where devitriflcation ofthe envelope Still another feature con- 2 shows such combination Theelectrode contors are connected to external contact caps I, 8.

At the respective ends of the envelope 2 and surrounding the electrodesis a quantity of mercury as shown at 9, l0. Part of the mercury iscontained in a pocket I! whereby the amount of mercury is adjustedduring the manufacture of the lamp. The electrodes 3, 4 project aboutone millimeter beyond the mercury surface. The envelope also contains acharge of starting gas, such for example as argon or neon, at a pressureof about 50 millimeters of mercury. The lamp is supported byelectrically conductive supports l3, M, on the ends of which it is heldby spring clips l5, l6. Operating current is supplied by the conductorsIT, IS connected to the contact terminals i9, 20. The supports l3, M aremounted on an insulating base 2 l Such a device may be operated-at apressure exceeding 40 atmospheres and up to 200 atmospheres and higher.

Unless the envelope of such device is energetically cooled, it willcontinue to rise in tem perature upon being put into operation, thevoltage required to operate the device rising at the same time. The risein vapor pressure with increasing temperature would result inextinguishing the discharge after a short period of operation, or, ifsuificient voltage should be available, excessive rise of internalpressure would cause it to burst.

Efiective cooling and continuous operation may be obtained by directingsharply localized jets of compressed air, or other suitable coolingfluid, against the envelope of such device at the regions adjacent therespective electrodes. These jets of air, delivered by the nozzles 22,23 and supplied by a pipe 24, should be directed substantiallyperpendicular to the axis of the envelope. Although nozzles such asshown in Fig. 1 are ordinarily preferred, the jets may be modified insome cases as shown at 22 and 23", Fig. 6. Satisfactory jet cooling hasbeen afiorded by maintained pressures of to 40 pounds. The jets of airmay have a diameter of about 50 to 80 mils. Preferably the centers ofthe respective jets of air are located opposite the ends of the respctive electrodes. When the ends of the nozzles are lengthened to formslits, as shown in Fig. 6, a modifying efiect can be exerted upon thevapor pressure and electrical characteristics of the lamp. For example,if the slit is positioned to direct the jet against a portion of theenvelope adjacent unvaporized mercury, then the vapor pressure can'bemaintained at a lower value.

The nozzle openings should be spaced closely adjacent the surface to becooled. A spacing of 1 to 2 millimeters ordinarily is satisfactory.Apparently a layer of warmed air, which tends to normally adhere to" thesurface to be cooled, must be effectivelyand rapidly eroded away. Thejets of pressure air have an effective bufling action which we havefound to be absent in the usual forms of air circulation.

Surprisingly, such localized jets adequately cool the envelope portionbetween the regions on which the jets impinge. As shown in Fig. 2, thedescribed lamp and the jet-cooling adjuncts may be mounted in a lightprojector having a housing 26 provided with the usual reflector (notshown) and mounted on the supports 21, 28.

The lamp shown in Fig. 1 can be operated with a lighting efiiciency of86 lumens per watt of consumed electric energy and with brillianciesover 50,000 candles per square centimeter. Because of this highbrightness, it is well adapted for use insearchlights;

delivered by two nozzles 3!, 32 extend linearly substantially over theentire discharge distance between the electrodes. The cooling jets ofair' or other suitable fluid preferably are delivered tangentially asshown in Fig. 4. In Fig. 5 is shown in perspective the nozzle 3! withits slit-shaped opening 34 carried by the supply tube '35. Whenemploying a slit-shaped nozzle the width of the slit should bematerially less than the diameter of device to be cooled. In theparticular case illustrated, its width is about one-fifth the diameterof the lamp. In both modifications of our invention the portion of theenvelope of quartz, or other refractory material, extending between theelectrodes is cooled either locally or throughout its length by theimpingement of one or more highvelocity jets which, however, exert butlittle cooling effect on the masses of mercury or whatever vaporizablematerial may be employed in the device. Our copending divisionalapplication Serial No. 465,114, filed November 10, 1942, is directed tofeatures of our invention which are embodied in the devices illustratedby Figs. 3, 4 and 5.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A vapor electric device comprising an envelope, electrodes therefor,a current-carrying medium including mercury in said envelope, theresulting mercury vapor being at superatmospheric pressure under normaloperating conditions, cooling means including nozzlesterminatingrespectively opposite said electrodes closely adjacent said envelope andhaving an opening of 'such small dimension that a jet of air issuingtherefrom impinges exclusively on said envelope, and means for supplyingair thereto at a pressure sufiicie'ntly high to maintain the vaporpressure v in said envelope below a predetermineddischarge-extinguishing limit.

2. A vapor. electric device comprising an envelope, electrodes thereinspaced apart, a current-carrying medium in said device including avaporizable material which in a condensed state surrounds saidelectrodes at least in part and cooling means constructed to supply jetsof gas under pressure directed against the parts of the envelope whichare immediately adjacent said electrodes and-having at least onedimension which is relatively small with relation to the surface beingcooled.

3. A high pressure vapor electric lamp comprising a tubular quartzenvelope, electrodes hav- Y ing conductors sealed into the wall of saidenvelope, a starting gas in said env'elope, bodies of mercury thereinrespectively surrounding said conductors and being sufficient inquantity to produce under operating conditions a vapor pressure of at,least several atmospheresand means for directing against said envelopeat regions adjacent said respective mercury bodies constricted jets ofcooling gas at'a pressure of at least about 10 pounds having asectionalarea less than the surface receiving the local impingement of said jets.

4. A high pressure vapor electric discharge device comprising anelongated tubular envelope,

: electrodes having stems respectively sealed into said envelope at theends thereof, a filling for said envelope comprising a material which isvaporizable at the operating temperature of said envelope, and coolingmeans starting gas and a constructed to project localized jets ofcompressed air against said envelope at regions adjacent said electrodesand substantially perpendicular to-an axis passing through saidelectrodes.

5. A high pressure mercury vapor lamp comprising an elongated tubularenvelope which is capable of withstanding an internal pressure of about40 to 200 atmospheres, electrodes of tungand maintaining the pressuresten therein having conductors sealed into the porizable material, whichmethod consists in carby the impingement of constricted jets of air reprying away heat irom'said envelope by the impingement o! constrictedjets of air thereon at regions adjacent said electrodes, the distancebetween said envelope and the base of said jetsand the area ofimpingement of said jets being substantially the same-as the crosssection thereof, of. compressed air for said jets at about 10 to 40pounds,

7. A method of operating an electric discharge device comprising anenvelope of capillary di-- mansions containing electrodes positionednear the ends thereof, and being provided with a starting gas and aquantity of mercury, method consists in operating said device with anenergy input of at least about 200 watts per centimeter of dischargecolumn, cooling said device spectively directed externally against theelectrode regions of said envelope, so regulating the length of saidjets that the area of impingement thereof is substantially the same asthe diameter thereof, and maintaining the velocity of air delivery ofsaid jets sumciently high to prevent the voltage required to maintain adischarge between said electrodes from a predetermined value.

. T. GORDON. WILHS R. WHITNEY.

which rising above

